SIMULATION OF THE ENERGY-LEVEL SCHEME OF ND-3+ AND EU-3+ IONS IN RARE-EARTH ORTHOVANADATES AND PHOSPHATES

The absorption spectra of the Nd3+ ion in the tetragonal xenotime-type NdVO4 and in the monoclinic monazite-type LaVO4, LaPO4 and NdPO4 as well as the luminescence of the Eu3+ ion in LaVO4 and LaPO4 were measured and the spectra were analysed according to the appropriate symmetry of the RE site. In addition to pure zero-phonon electronic lines the absorption spectra of the Nd3+ ion showed extensive vibronic side bands which were identified with the aid of the measured Raman scattering spectra of LaVO4:Nd3+ and NdVO4. Based on the energy level schemes derived from the absorption and luminescence spectra the parametrization of the free-ion and crystal-field effects were carried out with good results as indicated by the low RMS deviation values. The parameter sets for Nd3+ and Eu3+ ions in the same matrices are consistent with each other but no correlation was found between sets for matrices of different structures.